B-Physics at D

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B-Physics at DØRecent Results Plans
Hal Evans (for the DØ B group) Columbia U.

• B-Physics the DØ Detector
• Recent B-Physics Results
• Rare Decays
• Lifetimes
• Mixing
• Planning for the Future

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The Data Set
Coming Soon 610 pb-1
Analyses Presented Here ? 470 pb-1
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DØ Detector (the cartoon)
Forward Scint
Central Scintillator
Forward Mini-drift chambs
Central PDTs
Shielding
Calorimeter
Tracking Solenoid(2T), Silicon,FiberTracker,Presh
owers
New Electronics,Trigger,DAQ
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Tracking
250 pb-1
? 60 MeV

• 2 T Magnetic Field
• track reco to PT 180 MeV
• Silicon 2.7 9.5 cm (barrel)
• 6 barrels / 4 layers disks
• 793K chans (most 2-sided)
• Layer 0 this fall (r 1.7 cm)
• Fiber Tracker 20 51 cm
• 8 double layers axial stereo
• 77K channels
• Pre-Shower
• scintillating strips
• central forward / axial stereo

Large Acceptance ? lt 3
55?m(Pt 1GeV)
10?m
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Muons
P gt 3.5 GeV
P gt 1.5 GeV
? 2

• Large Coverage ? lt 2
• High Efficiency
• High Purity gt60 1-? _at_ L1

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Trigger

• Main B-Physics TriggersSingle- and Di-Muon
• Bs Mixing Data Set
• 67 Di-Muon
• 25 Single-Muon
• 8 other (?jet)

Detector
Level 1
Level 2
2.5 MHz
2.5 kHz
1 kHz
CAL
L1Cal
L2Cal
CalTrk
c/f PS
L1PS
L2PS
CFT
L1CTT
L2CTT
Typical Rates (Hz) at L 4?1031 cm-2s-1 Typical Rates (Hz) at L 4?1031 cm-2s-1 Typical Rates (Hz) at L 4?1031 cm-2s-1 Typical Rates (Hz) at L 4?1031 cm-2s-1
Trigger L1 L2 L3
dimuon 50 15 4
single mu 120 100 50
Total 1600 800 60
SMT
L2STT
L1Mu
MU
L2Mu
FPD
L1FPD
Global L2
L3 limit 50 Hz ? prescale !
Framework
Lumi
Level 3
50 Hz
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DØ B-Physics Results
? Differential X-Section 160 pb-1 PRL 94 (2005)
Bs ? Ds1(2536) ? v X 485 pb-1 preliminary
Bc Semileptonic 210 pb-1 preliminary
B ? D 250 pb-1 preliminary
B 350 pb-1 preliminary
X(3872) 230 pb-1 PRL 93 (2004)
Ds ? ? ? and D- ? ? ? 508 pb-1 preliminary
Bs ? ? ?- ? 300 pb-1 preliminary
Bs ? ? ?- 300 pb-1 preliminary
240 pb-1 PRL 94 (2005)
Bs ??/? 450 pb-1 preliminary
Bs ? Ds ? X Lifetime 400 pb-1 preliminary
B/B0 Lifetime Ratio 440 pb-1 PRL 94 (2005)
?b ? J/? ? Lifetime 250 pb-1 PRL 94 (2005)
Bs ? J/? ? Lifetime 220 pb-1 PRL 94 (2005)
Bs Mixing using Ds(??) ? X and OST 460 pb-1 preliminary
Bs ? Ds(KK) ? X Reconstruction 200 pb-1 preliminary
Bd Mixing 250 pb-1 preliminary
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Bs Galore !
Mode evts / 100pb-1
J/? ? ? ?- 1.14 M
B ? J/? K 1700
Bd ? J/? K0 740
Bd ? J/? K0S 40
Bs ? J/? ? 100
?b ? J/? ? 25
Bc ? J/? ? X 65
X(3872) ? J/? ? ?- 230
B ? D ? v 210
B ? B ? 150
Bs ? Ds1 ? X 4
B ? D0 ? X 46.2 K
Bd ? D- ? X 10 K
Bs ? Ds(??) ? X 2900
Bs ? Ds(KK) ? X 2500
Bs ? Ds1(2536) ? v X
485 pb-1
Ds1 ? D KS0
Signal 18.5 5.5 (3.4?)
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FCNC Heavy Flavor Decays
Bs ? ? ?-

• SM BR (3.41.5)?10-9
• Enhanced at large tan? (MSSM ? tan6 ?)
• CDF-II BR lt 1.5?10-7

Bs ? ? ?- ?

• SM BR 1.6?10-6
• Smaller Enhance at large tan?
• CDF-I BR lt 6.7?10-5

D ? ? ?- ?

• SM BR 1.0?10-6 (dominated by long distance)
• Enhanced in e.g. RPV SUSY
• FOCUS BR lt 8.8?10-6

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Bs ? ??- and ??-?

• Preselection
• vertexed ??- PT? gt 2.5 GeV, ? lt 2.0
• pair of opp chrg tracks (?)
• PTB gt 5 GeV
• Final Selection Discriminants
• Isolation of ??-(?)
• Pointing Angle ?(Lvtx , P)
• Lxy Signif Lxy / ?Lxy
• Normalization Channels
• ??- B ? J/? K
• ??- ? Bs ? J/? ?

??- Events
Bs???-
300 pb-1
Bs???-?
closed
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Limits
Bs ? ? ?- ? Normalization
Bs ? ? ?- Normalization
Bs ? J/? ?
NBs 74 11
Channel Eff wrt Pre-Sel N(bgrd) N(data) BR Limit (95 CL) SM Pred
? ?- 38.6 4.3 1.2 4 3.7 ? 10-7 3.4 ? 10-9
? ?- ? 52 5.1 1.0 blind 1.2 ? 10-5 (ave) 1.6 ? 10-6
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Ds ? ??-? and D ? ??-?
508 pb-1

• Select D(s) Signal from ?(??-)? cands w/
  Likelihood
• D Isolation PT(D)/?PT(cone)
• Lxy Signif SD Lxy/?Lxy
• Pointing Angle ?(Lxy,PT)
• Signif Ratio S?(imp-par)/SD

Signal(Ds??? MC)
Background(MD sidebands)
Lsig / (Lsig Lbgd) d
World Best Limit
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Lifetime Roundup
DØ Lifetime Measurements vs HFAG World Averages
World Best
errors scaled x10 for display purposes
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Bs ? Ds ? v X Lifetime
Right SignSideband
300 pb-1
Signal Region 35955 evts
Wrong SignSideband
D- ? ? ?- 1300 223
Ds- ? ? ?- 5153 265 450

• Unbinned logL Fit for ? using
• signal region
• wrong- right-sign sidebands( to constrain bgrd
  PDFs)
• f(signal) from Mass fit

• Bs ? Ds(??) ? v X Selection
• no lifetime biasing cuts

?(Bs) 1.420 0.043 0.057 ps
World Best Measurement ! HFAG ave now 1.472
0.045
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Bs Lifetime Difference

• Bs ? J/? ? (P ? V V)
• CP-Even S,D waves
• CP-Odd P wave
• relative contributions ? CP states of Bs

• Observed Distribution
• Transversity Angle Fit
• ?? b/w M eigenstates
• R? A?(0)2

CP-Odd
CP-Even
Detector effects
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Fits to Data

• Fit Results

• Data Set 450 pb-1
• 9699 candidate events
• 48332 Bs ? J/?(??-) ?(KK-)
• Fit to M(Bs), ct0, cos?
• Free params
• fsig, ?ave, R?, ??/?, M(Bs)
• resolution bgrd params

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Comparing to the SM

• Flavor Specific Decays also constrain ??/?
• Using PDG ?(Bs?DslvX)
• Assuming SM ? CPV ??

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Bs Mixing Analysis

• Data Selection
• Bs ? Ds- ? v XDs- ? ?(KK-) ?-
• no explicit trigger required
• some ?-dependent cuts(effects cancel in Asym)
• Opposite Side (Muon) Tagger
• Q(jet) containing muon
• PTrel ? Q(?)
• Q(secondary vertex)
• Eff Dilution from Data
• ? Ntag/Ntot 5.1
• D 2? - 1 44.8(? Ncorrect/Ntag)

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Measure Tagging using Bd and B
? D0 X Sample(85 Bd - 15 B)
? D0 X Sample(85 B - 15 Bd)
?u 0.734 0.015
?d 0.724 0.021 use in Bs fits
?md 0.558 0.048 ps-1
(HFAG 0.509 0.004 ps-1 winter 05)
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Bs Results
DØ Prelim Result 95 CL ?ms gt 5.0
ps-1sensitivity 4.6 ps-1
Asym vs VPDL
460 pb-1
Expected Limit Comparison
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DØ Upgrades for High Luminosity

• Trigger (mainly L1)
• allows viable trigger list as L gt 2?1032
• L3 Bandwidth Upgrade
• current limit for B-Physics triggers is at L3
• proposal add dedicated 50 Hz of output bandwidth
• Silicon Layer-0
• integrated radiation dose ? inner SMT layer dies
• add new, rad hard Layer-0 at R 1.7 cm
• Impact Param 55?35 ?mat 1 GeV

2.9?1032 cm-2s-1
2?1032 cm-2s-1
we are here
dE/dx using SMT
golf ball size !
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Reach in Bs Mixing

• In Review Now (for EPS 05)
• add KK mode
• improved tagging (add electrons more vars)

Further Down the Road
Toward 1 fb-1
cover full SM range(but need to establish
hadronic modes)
semileptonic sens 12 ps-1 with 1 fb-1s
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Lifetime Futures
Bs Lifetime Projections Bs Lifetime Projections Bs Lifetime Projections Bs Lifetime Projections Bs Lifetime Projections
Mode Lumi (fb-1) Stat (ps) Syst (ps) Tot (ps)
Ds ? X 0.4 0.043 0.057 0.071
4.0 0.013 0.03 0.034
Ds ? 4.0 0.04 0.01 0.04
reduction coming soon
450 pb-1
??/? Projections ??/? Projections
Lumi (fb-1) Error on ??/?
0.45 0.45
2 0.12
4 0.08
8 0.06
Theory 0.12 0.05
DØ ?fs ??/?

• Assumes
• Layer-0 3-angle Fit for ??/?

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More Crystal Ball Gazing

• Most DØ B-Physics Results are Statistics Limited
• Rare Decays
• reoptimize selections, F-B Asyms, KS??-,
  K??-,
• broaden charm FCNC analysis
• ??/?
• 3-angle fits, Separate Lifetimes for CP-state
  (??, Ds()Ds())
• Integrated CP asym in semileptonic, ?s,
• Bs Mixing
• more modes KK,3?,KsK Bs ? Ds ?
• better tagging electrons, more variables
• event-by-event likelihood fits
• (some) Others
• B, D, Ds1 move from observation ? measure
  properties
• J/? ? Polarization and b cross-section
• Bc semileptonic and hadronic decays
• make more use of neutral particles (?, ?0, ?c?J/?
  ? )

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Conclusions (Beginnings ?)

• DØ Physics Program is Hitting its Stride
• detector well-suited to many measurements
• Several World Best Results
• D ? ? ?- ? Bs Lifetime
• Interesting New Results Just Around the Corner
• improved ?ms, rare decays, for EPS 05
• DØ Upgrades for High Lumi ? Improve Performance
• trigger, layer-0, L3 bandwidth upgrade

Stay Tuned !
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Backup Slides
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Low PT Tracking
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B ? ? ?- (?) Final Discriminants
Bs ? ? ?-
Bs ? ? ?- ?
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Bs Mixing Details